As surface treatment apparatuses for surface-treating small objects, apparatuses disclosed in Patent Documents 1 and 2, for example, are known. In each of these apparatuses, while a treatment cell containing small objects is rotated, a surface treatment liquid is injected into the treatment cell, thereby surface-treating the small objects.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 11-505295    [Patent Document 2] U.S. Pat. No. 5,879,520